Listening for Alien Life: Could
New Tech Detect Microbe Movements?
, Space.com's Space
| October 01, 2015
Inventor Dan Slater uses remote acoustic sensor (RAS)
technology during a test-firing of the five-segment rocket motor
headed for use on NASA's Space Launch System booster. Credit:
PASADENA, California — Spacecraft may one day be able to detect
alien life by listening to the sounds microbes make. Scientists are
testing a new microphone technology called the remote acoustic
sensor (RAS), which is capable of capturing sounds within extreme
and often inaccessible aerospace environments. A miniaturized
version of the device could theoretically make its way to Mars or to
ocean-harboring moon, Europa, to listen for signs of life,
"If there's life, and if it moves, it may make RAS-detectable
sounds," said RAS lead technologist Dan Slater, an independent
consultant based in La Habra Heights, California. Slater presented a
review of his work on the RAS concept here Sept. 2 at the American
Institute of Aeronautics and Astronautics' (AIAA) Space 2015
The RAS detector assembly is sensitive to small
audio-frequency variations in electromagnetic energy, Slater said.
The technology becomes even more interesting and useful, he added,
when combined with time-synchronized high-resolution imagery of the
To showcase his idea, Slater has used a ground-based, long-range RAS
telescope to obtain visual and audio recordings of a SpaceX Falcon 9
rocket launch that took place in September 2013. He also monitored a
test earlier this year of a rocket motor that will be incorporated
into NASA's heavy-lift Space Launch System rocket.
A ground-based long-range remote acoustic sensor (RAS)
telescope provided visual and audio views of the September 2013
launch of a SpaceX Falcon 9 rocket. This example shows
main-engine cutoff, stage separation and second-stage engine
start high above the Earth. Credit: Dan Slater
RAS technology has also recorded the sound of a plane landing at Los
Angeles International Airport, capturing the audio from the summit
of Mount Wilson, some 28 miles (45 kilometers) away. A spectrogram
produced from the recording shows several descending tones that were
produced by the landing jet, Slater said.
A remote acoustic sensor (RAS) view of the acoustic activity
generated by a rotifer of the genus Cothurnia, a protozoan that
uses whirling cilia to pump food and water through its digestive
system. RAS can detect the low-frequency modulations produced by
the spinning cilia. Credit: Dan Slater
Slater has turned his attention to the microbial world as well,
recording the acoustic activity produced by a 75-micron (0.003
inches) rotifer, a type of protozoan, of the genus Cothurnia.
As for his rocket-recording work, "generally, anything with flames
tends to produce strong RAS audio," Slater said.
The flames and exhaust plumes produced by rockets,
both liquid- and solid-fueled, are therefore usually very strong RAS
emitters. Similarly, strap-on solid-rocket motors will produce very
strong RAS audio with interesting stereophonic sound behavior at the
burnout, jettison and post-jettison stages.
RAS technology could also observe a number of other rocket
phenomena, including engine-bell vibrations and turbo-pump
oscillations, Slater said.
Ears wide open
Work is underway to tie RAS to a flight camera, said Rex
Ridenoure, CEO of Ecliptic Enterprises Corporation in Pasadena.
Ecliptic, a space-avionics and sensor-systems company, builds
"RocketCam," which is widely used on board rockets, spacecraft and
other remote platforms
The idea is that RAS/RocketCam should be able to hear rocket-stage
shutdowns and various spacecraft separation and deployment events.
"Insertion of RAS into Ecliptic's RocketCam product family is
progressing well, and we're actively seeking near-term demonstration
opportunities on rockets and spacecraft," Ridenoure told Space.com.
"RocketCam provides eyes for a wide variety of space activity … RAS
RAS could also likely detect the high-speed entries into Earth's
atmosphere of spacecraft and asteroids. And a space-based
RAS/RocketCam may also be able to discern many objects and phenomena
at night, such as cities, urban activity and lightning. Daytime
detections could include lightning and possibly distant aircraft.
RAS-equipped spacecraft could also be useful beyond Earth orbit,
Slater said, potentially capturing natural sounds at asteroids,
comets, planets and moons — including, potentially, vibrations
produced by alien
life on Mars, Europa or Saturn's ocean-harboring moon,
It's feasible to listen for such sounds of life from an orbiting
spacecraft, Slater said. A miniature RAS sensor could also be added
to a spacecraft that lands on an alien world.
All of these possibilities are intriguing, said David Klumpar,
a research professor of physics and director of Montana State
University's Space Science and Engineering Laboratory in Bozeman.
"We are actively pursuing these and other science applications at
Montana State University for implementation on CubeSats,"
Klumpar told Space.com.
RAS has the potential to be "one of the most disruptive new
technologies of the late space age," Klumpar said. "One can imagine
applications in many arenas."
What excites Klumpar the most, he said, are the potential science
applications. For example, RAS could help scientists listen remotely
to natural phenomena such as lightning, the northern and southern
lights, and solar eruptions, to name only a few, he concluded.
Leonard David has been reporting on the space industry for
more than five decades. He is former director of research for
the National Commission on Space and is co-author of Buzz
Aldrin's 2013 book "Mission to Mars – My Vision for Space
Exploration" published by National Geographic with a new updated
paperback version released in May 2015. Follow us @Spacedotcom,
Originally published on Space.com.